Thermal conversion of hydrocarbons promoted by explosive organic nitrogen compounds



Patented Feb. 10, 1948 7 BONS PROMOTE!) BY EXPLOSIVE GANIC NITROGEN COMPOUNDS I OR- Carlisle M. Thacker, Highland Park, and Hillls 0. Folklns, Evanston, Ill., assignors to The Pure Oil Company, Chicago. 111., a corporation of Ohio No Drawing. Application March 14, 1942,

Serial No. 434,790

.8 Claims. (01. 269 -683) This invention relates to thermal reactions of hydrocarbons and more specifically to means for more efliciently carrying out such reactions with the aid of reaction promoting. agents whereby lower temperatures and shorter reaction periods may be employed or higher yields obtained under given reaction conditions than those required for the ordinary unpromoted reaction. V

Various thermal hydrocarbon reactions are rather well known.- The thermal treatment of high boiling hydrocarbons whereby to produce hydrocarbons of lower molecular weight such as gasoline, largely by scission of carbon-to-carbon bonds, is the basis of cracking processes. Similarly, normally gaseous hydrocarbons may be thermally treated to produce normally gaseous olefins and paraiiins'and also hydrocarbons of higher molecular weight through further reactions ordinarily referred to as polymerization. The proportion of such higher boiling hydrocarbons obtained in gas conversion processes is ordinarily rather small when the conversion is effected at low pressures, but may be materially increased through the use of higher pressures. Normally liquid hydrocarbons of gasoline boiling range obtained by such processes are ordinarily used as motor fuel and normally gaseous olefin hydrocarbons may be converted into motor fuel boiling range hydrocarbons by polymerization or employed forany one of several other well known uses.

It is known that thermal reactions oi. satcatalysts, are within the scope of the term "thermal hyd. ocarbon conversion" as used herein.

This invention provides a diilerent method of bringing about thermal hydrocarbon conversion reactions under milder conditions than those required for the ordinary unpromoted reactions or which increase the 'rate or conversion under a urated and unsaturated hydrocarbons may be 1 carbons in the absence of the catalyst. Similar improved results may be obtained by the'use of appropriate catalysts in cracking, polymerization, isomerization, alkylation and other well known thermal hydrocarbon conversion reactions. Such reactions, so long as they are eiiected only at temperatures above, atmospheric, whether eflected in the presence or absence of given set of reaction conditions. ed by the use of certain reaction promoting agents which when employed in admixture with the hydrocarbons either materially reduce the severity oi the conditions required to produce a given yield of desired product, or under a given set of reaction conditions materially improve the yield of desired products obtained.

An object of this invention is to increase the rate or thermal conversion reactions of hydrocarbons.

Another object is to efl'ect thermal conversion of hydrocarbons under milder conditions than those required for the ordinary unpromoted reactions.

Another obJect of this invention is to effect the cracking of petroleum hydrocarbons under lower temperature conditions than can ordinarily be employed to obtain substantial ields of decomposition products.

Still another object of this invention is to effect the alkylation of hydrocarbons at a higher rate than that ordinarily obtainable under a particular set of reaction conditions.

A further object of the invention is. to convert aseous hydrocarbons into unsaturated hydrocarbons and also into normally liquid hydrocarbons with higher yields than those ordinarily obtainable under a given set of reaction conditions.

Still another object or this invention is to provide a method of'increasing the rate of conversion of normally gaseous hydrocarbons into lighter unsaturated hydrocarbons and also into normally liquid hydrocarbons by the use of reaction promoting agents and to obtain higher yields than are obtainable under the same conditions in the absence of reaction promoting agents.

Other objects of the invention will be apparent as the description proceeds.

It has now been found that the thermal conversion of hydrocarbons may be promoted by organic nitrogen compounds which are decomposable under conversion conditions'into decompo- I 3. sition products which are inthe same phase as the hydrocarbons undergoing. conversion. The nature of the organic nitrogen compounds may vary widely. Those organic nitrogen compounds which contain only the elements carbon and hydrogen in addition to the nitrogen such as hydrocarbon amino compounds, are particularly eflective. Hydrocarbon nitro compounds (not including the isomeric nitrites) have also been found to possess unusual merit. Among thehydrocarbon nitro compounds which may be used are nltromethane, dinitromethane, trinitromethane, tetranitromethane, nitroethane, F l-nitropropane, 2-nitropropane and nitrobenzenes. Of" these compounds. nitromethane has been found to be unusually eflicacious. Examples of suitable hydrocarbon amino ..compounds are dimethylamine, triethylamine, diethylaminej trimethylamine, tripropy1amine, -mono-, di-. and triallylamine; di-n-propyl, di-iso-propyland isopro- Dylamine. Of these amino compounds triethylamine has been found to be unusually eflectivei g Organic compounds which decompose'with explosive violence are particularly effective in aiding in the cracking of hydrocarbons containing 3 or more carbon atoms per molecule. pounds which may thus be used are those compounds which are ordinarily referred to as high explosives such as nitroglycerin, trinitrotoluene, trinitroxylene, tetryl, picric acid, cellulose hexanitrate,- nitromannite and others. The reason for this unusual eflect of the explosive compounds is not known at the present time although it is thought that the shock of the decomposition of the explosive is communicated to the intimately associated hydrocarbon molecules undergoing decomposition, thus facilitating 'scission of the carbon to carbon bonds.

The'thermal reactions which may be promoted as previously described may be conducted under 40 varying conditions of time, temperature and pressure. In general, cracking reactions are effected under conditions of relatively low super-atmospheric pressure when the production of hydrocarbons of lower molecular weight is desired.

'However. the reaction may be conducted at rela- The com- 4 particularly eflective in facilitating the cracking oi hydrocarbons having 8 or'more carbon atoms per molecule. Ordinarily, the reaction promoting agents are employed in relatively small amounts such as from about 0.25% to 8 mol%- of the hydrocarbonsundergoing conversion. a

In order to demonstrate the eflectiveness o1=the reaction promoting agents employed in this.invention. numerous experiments were carried out under static conditions in which a hydrocarbon, preferably n-butane. was decomposed in a reaction chamber under conditions or elevated teniperature and the degree and rate oi decompositionmeasured by, the analysis of the resultant products and the measurement or the rate at which pressure increase occurred. -In order to obtain a comparison between the unprbmoted and promoted reactions, similar experiments were carried out i.n the presence of various reaction promoting agents. The following is a description of the method employed:

A reaction chamber, provided with suitable heating elements, was evacuated to a pressure of the order oi. 10- mm. and a mixture or n-butane containing a definite amount or reaction promoting. agent admitted to thereactor. The temperature of the reactor was maintained suillciently high to eflect a substantial degree. of decomposition of the "xi-butane. After charging the mixture oi n-butane and reaction promoting agent to the reactor maintained at suitable temperature. the time in minutes required for a given increase in pressure was determined. Mixtures of the reaction promoting agents diluted with ap-' propriate amounts oi oxygen-free nitrogen were similarly treated in order to measure the rate oi pressure increase due solely to the reaction promoting agent. The increase in pressure due to the reaction promoting agent per se was determined as shown in Table land was deducted from the increases in pressurenoted when mixtures of the reaction promoting agent and butane were By this means it was charged to the reactor. possible to estimate the effect oi. the various reaction promoting agents on the rate of decomposition of the n-butane. Analysis of the conversion products in each caseindicated the nature of the conversion products obtained as a result of the decomposition reactions. Table II shows the results obtained on a number of runs in which n-butane of 99% purity was decomposed at a temperature of 525 C. and'at pressures slightly above atmospheric-i. e., about 800-900 mm. All of the runs up to and including nm 74 were carried out in asteel reaction chamber fabricated from alloy steel containing 18% chromium and 8% nickel. All other mm were carried out in a Pyrex glass reaction chamber.

\ Table I l v I, Bun No.---.. s1 71 75 I 130, 144

bars: I l I 4 Per cent Nitrogen 00.0 97.0 07.0 07.0 97.0..... 07.0. Per cent Bensitizer 1.0. 3,0 .0 8.0.. mm 8.0.... 3.0. Sensitirer Triethyl- Trimethyl- Dimethyl- N i t r o Nitro- A 11 y l amine. amine. amine. methane ethane. amine Per cent Per cent Per cent Per cent Per cent Per cent Time in Minutes Pressure Pressure ressure Pressure Pressure ressure Increase Increase crease crease Increase Increase 0.03 1.25 1.85 0.95 1. 57 0.00 1. 0e 2. 43 2. a1 0. 05 1. 57 0. s3 1. 00 8. is 2. 44 0. 96 1. b7 0. so

Bun N0 J- 59 60 U 01 I Per cent n-Butene 100 00. 0 100. 0 00.0 N. 0 Per cent Sensitleer 0.0 1.0 0.0 1.0 2.0 Benzitleer Triethyl- 'lflmeth7l- Trlmethylemlne. mine. mine Net'llme Nez'llme Net'llme Net Time Net'rlme 2. 86 1. 09 2.8 1. 90 -1. 70 use 3.51 we no 6.40 26.0 22.!) 10.80 22.8! 19.02 15.0 One Anelyels: A

PereentOO 0.0 0.0 0.0 0.2 0.2 0.8 23.6 23.0 10.0 34.1 28.1 0. 3 0. 8 0. 2 0. 2 0. l 0.2 0. 6 0. l 1.8 1. 1 76. 9 76. 0 74. 4 74. 2 16. 5

97. 0 100. 0 99. 0 N. 0 I 97. 0 8. 0 0. 0 l. 0 7 2. 0 8. 0 Trlmethyl- Dlmethyl- Dimethyl- Dimethylamine. mine. amine. emlne.

Net Time Net Time Net Time Net Time NetTlme 1.54 as: 2.40 2.44 1. 01 4. 59 8. 38 7. 06 O. H 6. 14 2. 26 2 1. 76 19. SI l8. 44 17. 47 0. 8 0. 1 0. l 0. l 0. 1 23. 2 24. 4 73. 4 22. 4 21. 5 0. 3 0. 1 0. 1 0. l 0. 5 I. 3 0. 9 2. 3 3. 1 2.7 73.9 74.6 74.1- 74.3 75.2

. Run No, 119 120 131 I22 123 7 Charge:

Per cent n-Butane 100. 0 99. 0 no 97.0 90. 5 Per cent Beneitiur 1.0 2.0 8.0 0.5 'Seneitimr Nltro- Nitro- Nitro- Nitromethane methane meehene methane mm Pressure Increase Net Tline Net Time Net Tune Net Time Net Time 2.0 o.s 0 o.e o.e

7. 0 2. 00 0. 53 0. 6 4. 05 2o. 0 16. 00 ll. 1 11.0 17. 70

0. 1 0. 0 0 0 0 0 0. 0 22. 7 22. 6 23- 6 22.0 23. 1 0. 1 0. 1 0. l 0. l 0. 0 1.1 1.8 1.1 1.8 1.2 76. 0 76- 0 78- I 76. 4 75. 7

in no 124 12o 121 us 129 Oherge: 7

Per cent mBntme 99. 76 v 100- 00 99. 0 N. 0 97. 0 Percent 0.25 1.0 2.0 3.0 Senelther Nitro- Nltm- Nitrw Nltromethane ethane ethane etheue Per cent Pmemre mm 9 Net Time Net Time Net Time Net Time Net Time (0. 5 2. 2 0. I 0- 5 0. 5 6.07 7.4 4.45 3.96 1.0 19. 70 2o. 7 I8. 26 14- $5 12. 85

0. 1 0. I 0. l 0- 1 0. 1 Gen 24. 0 23. 8 I. 3 32- 4 22. 1 0. l 0. I 0.3 0. l 0. 1 H 1- 2 7 1. 2 1. 4 1. l 1. 1 B8. 74. 6 74.8 7. a 79-9 79. 9 W

' From the data, presented in Table 11 it will be seen that the use-oi reaction promoting agents in accordance with this invention materialiyincreased the rate or decomposition of butane when used in proportions of about-0.25 to 3 mol at temperatures oi 525C: Note; for example, that the rate 01 decomposition of butane in run 59 was such that 22.8 minutes were required for a increase in pressure on the reactor, whereas in run 60"which was made under the same conditions as run 59 but in which 1%.0! triethylamine was employed as a reaction promoting agent, the decomposition rate was much higher since the' time required for 25% pressure increase on the reactor was only 10.89 minutes. or less than half.

the time required in run 59. Similar beneficial the reaction promoting agents. In all cases substantial amounts of oleflnic hydrocarbons were present in the conversion products.

I 9,485,760 7 Q J I a A 4 ration-Confined as. m w. w m

= Persona-Butane 100.0 90.0 can 01,0

PsreentBeoltissr 1.0. 2.0 8.0 f r Allylsmine Allylsmine Allylsmins' Pu Omtilzesmre Incense NetTims Net Time Net Time 7 Net Time as. sec 1.41 Lee Lee 7.68 4.61 4.71 l. d m NJB- 14.66 18.? 12.46

, w cen .eo. 0.0 0.1 so 0.0 0 In. I 22.4 31.7 21.9 22.8 C6 0-2 0.1 0.1 0.1 Hg. 0.0 1.2 0.7 1% 1e: 70.0- 11.: 7e.

'3. Process in accordance with claim 2 in which the explosive is used in amounts of 0.25 to 3 mole perceg: based on thehydrocarbon.

4. e method 0! promoting thermal cracking oi hydrocarbons which comprises subie'ctins said jhydrocarbons to cracking ,temperature in the presence oi-a small amount of trinitrotoluene.

5. The method 01 promoting thermal crackin of hydrocarbons which comprises subjecting said hydrocarbons to cracking temperature in the presence of a small amount or trinitro xyiene.

6. In a process for thermally crackini hydro- .carbons containing 3 or more carbon atoms per molecule the step comprising increasing the rate of cracking under conditions at which unpromoted thermal cracking occurs at less than a desired rate by admixing with ehydrocarbons approximately .25-3 mole percent/oi an explosive nitrated benzene ring compound decomposable under said conditions into decomposition prodnote which are oi. the same phase as the hydro- While in the foregoing specific examples the I reaction promoting agents were employed to aid the thermal decomposition oi butane, it is to be understood that the reaction promoting agents may-similarly be employed to eflect other thermal hydrocarbon conversion reactions such as, for example, allwlation, the polymerization of unsaturated hydrocarbons and those reactions wherein the hydrocarbons undergo molecular rearrangement such as isomerization. It is apparent that many changes may be made in the details as set forth in the ioregoing description without departing from the spirit and scope of the invention as set forth in the following claims.

We claim:

1. The method of promoting thermal cracking.

of hydrocarbons which comprises subjecting said hydrocarbons to cracking temperature in the presenceoi asmall amount 0! nitroglycerin.

0! high explosive selected from the group 0011-,

sisting of nitroglycerin, trinitrotoluene, trinitroand nitromannlte.

carbons undergoing cracking.

CARLIBLE u: mom. nnms o. roams. Banana-noes CITED The following references are of record in the file of this patent:

} 1 UNITED STATES PATENTS Number Name Date' 236,995 De Schmedt Jan. 25, 1881 2,117,022 Cramer May 10, 1938 2,259,630 Frey et a1. Cot. 21; 1941 v I FOREIGN PATENTS Number Country Date 320,421 Great Britain Oct. 7, 1929 OTHER. REFERENCES Cramer, J. A. C. 8., vol. 60, 1408-10 (1938) Heilbron, Dictionary of Organic Compounds.

Rice et al., Chem. Abs., vol. 29, 723 (1935) Rice et al., J. A. C. 8., vol. 55, 3898-9 (1983), Rice et al., J. A. C. 8.. vol. 56, 214-19 (1934) Sickman et al., Journal 01' Chemical Physics Vol.4 (1936) pp. 608-613. 

